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/*
* ProGuard -- shrinking, optimization, obfuscation, and preverification
* of Java bytecode.
*
* Copyright (c) 2002-2013 Eric Lafortune (eric@graphics.cornell.edu)
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package proguard.shrink;
import proguard.classfile.*;
import proguard.classfile.attribute.*;
import proguard.classfile.attribute.visitor.*;
import proguard.classfile.constant.*;
import proguard.classfile.constant.visitor.ConstantVisitor;
import proguard.classfile.util.SimplifiedVisitor;
import proguard.classfile.visitor.ClassVisitor;
/**
* This AttributeVisitor recursively marks all Signature attributes that it
* visits and that point to used classes.
*
* @see UsageMarker
*
* @author Eric Lafortune
*/
public class SignatureUsageMarker
extends SimplifiedVisitor
implements AttributeVisitor,
ClassVisitor,
ConstantVisitor
{
private final UsageMarker usageMarker;
// Fields acting as a return parameters for several methods.
private boolean attributeUsed;
/**
* Creates a new SignatureUsageMarker.
* @param usageMarker the usage marker that is used to mark the classes
* and class members.
*/
public SignatureUsageMarker(UsageMarker usageMarker)
{
this.usageMarker = usageMarker;
}
// Implementations for AttributeVisitor.
public void visitAnyAttribute(Clazz clazz, Attribute attribute) {}
public void visitSignatureAttribute(Clazz clazz, SignatureAttribute signatureAttribute)
{
// Only keep the signature if all of its classes are used.
attributeUsed = true;
signatureAttribute.referencedClassesAccept(this);
if (attributeUsed)
{
// We got a positive used flag, so the signature is useful.
usageMarker.markAsUsed(signatureAttribute);
markConstant(clazz, signatureAttribute.u2attributeNameIndex);
markConstant(clazz, signatureAttribute.u2signatureIndex);
}
}
// Implementations for ClassVisitor.
public void visitLibraryClass(LibraryClass libraryClass) {}
public void visitProgramClass(ProgramClass programClass)
{
// Don't keep the signature if one of its classes is not used.
if (!usageMarker.isUsed(programClass))
{
attributeUsed = false;
}
}
// Implementations for ConstantVisitor.
public void visitAnyConstant(Clazz clazz, Constant constant)
{
usageMarker.markAsUsed(constant);
}
// Small utility methods.
/**
* Marks the given constant pool entry of the given class.
*/
private void markConstant(Clazz clazz, int index)
{
clazz.constantPoolEntryAccept(index, this);
}
}
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